Currently, global, proper motion catalogs are limited to stars brighter than
visual magnitude 10.5. In order to increase our knowledge of
galactic kinematics as well as extend the optical reference frame,
proper motions of fainter stars are required.
A number of projects are underway at the USNO that will result in
accurate positions and proper motions for stars of much fainter magnitudes.
These projects include: new reductions of
Astrographic Catalogue (AC) data (average epoch about 1905);
measurement and reductions of
the USNO's twin astrograph plates taken in the early 1980's;
re-measurement and reduction of the Palomar Sky Survey plates; and a new
program
to accurately determine positions of all stars 14th magnitude and brighter
using the USNO's 8" astrograph with improved optics.
When combined, the results of
these programs will give astrometric data for millions of stars whose
current positions and proper motions are undetermined.

A cornerstone for proper motion determinations is the data contained in the
Astrographic Catalogue. The data's early epoch (about 1905), global
coverage and positional accuracy make them the best source of first epoch
positions for stars down to 13th magnitude.
Each of the 22 AC zones is being reduced independently, with corrections
being applied when needed for plate tilt, radial
distortion, coma, magnitude equations and other field distortions.
It is expected that the reductions of the entire AC, containing about
five million stars, will be completed by the end of 1996.